TY - JOUR
T1 - Hydrolytic Stability of Boronate Ester-Linked Covalent Organic Frameworks
AU - Li, Huifang
AU - Li, Haoyuan
AU - Dai, Qingqing
AU - Li, Hong
AU - Bredas, Jean-Luc
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Army Research Office[W911NF-15-1-0447, W911NF-17-1-0339]
PY - 2018/1/30
Y1 - 2018/1/30
N2 - The stability of covalent organic frameworks (COFs) is essential to their applications. However, the common boronate ester-linked COFs are susceptible to attack by nucleophiles (such as water molecules) at the electron-deficient boron sites. To provide an understanding of the hydrolytic stability of the representative boronate ester-linked COF-5 and of the associated hydrolysis mechanisms, density functional theory (DFT) calculations were performed to characterize the hydrolysis reactions of the molecule formed by the condensation of 1,4-phenylenebis(boronic acid) (PBBA) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) monomers; two cases were considered, one dealing with the freestanding molecule and the other with the molecule interacting with COF layers. It was found that the boronate ester (B–O) bond dissociation, which requires one H2O molecule, has a relatively high energy barrier of 22.3 kcal mol−1. However, the presence of an additional H2O molecule significantly accelerates hydrolysis by reducing the energy barrier by a factor of 3. Importantly, the hydrolysis of boronate ester bonds situated in a COF environment follows reaction pathways that are different and have increased energy barriers. These results point to an enhanced hydrolytic stability of COF-5 crystals.
AB - The stability of covalent organic frameworks (COFs) is essential to their applications. However, the common boronate ester-linked COFs are susceptible to attack by nucleophiles (such as water molecules) at the electron-deficient boron sites. To provide an understanding of the hydrolytic stability of the representative boronate ester-linked COF-5 and of the associated hydrolysis mechanisms, density functional theory (DFT) calculations were performed to characterize the hydrolysis reactions of the molecule formed by the condensation of 1,4-phenylenebis(boronic acid) (PBBA) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) monomers; two cases were considered, one dealing with the freestanding molecule and the other with the molecule interacting with COF layers. It was found that the boronate ester (B–O) bond dissociation, which requires one H2O molecule, has a relatively high energy barrier of 22.3 kcal mol−1. However, the presence of an additional H2O molecule significantly accelerates hydrolysis by reducing the energy barrier by a factor of 3. Importantly, the hydrolysis of boronate ester bonds situated in a COF environment follows reaction pathways that are different and have increased energy barriers. These results point to an enhanced hydrolytic stability of COF-5 crystals.
UR - http://hdl.handle.net/10754/627259
UR - http://onlinelibrary.wiley.com/doi/10.1002/adts.201700015/abstract
U2 - 10.1002/adts.201700015
DO - 10.1002/adts.201700015
M3 - Article
SN - 2513-0390
VL - 1
SP - 1700015
JO - Advanced Theory and Simulations
JF - Advanced Theory and Simulations
IS - 2
ER -